The present invention relates to a packing box.
The invention relates in particular to the transport of airmail.
Such boxes, designed to contain mail, must be reusable, lightweight and stiff, have high mechanical strength, be moisture-resistant, and be easy to handle and store.
The object of the invention is to provide a packing box that is relatively easy to produce, is of low cost and satisfies the requirements stated above.
To this end the subject of the invention is a packing box of polygonal general shape that widens out, made from a flat cellular plastic blank that is cut and folded, comprising, on the one hand, a base and side walls, these walls being formed from side panels of the blank that are joined together and, on the other hand, an outer reinforcing frame, used for holding the box, that runs around the side walls and comprises frame members joined together and fixed to the side walls.
In certain particular embodiments, the box may comprise one or more of the following features, taken in isolation or in all technically possible combinations:
the frame members are formed from folded flaps extending from side panels of the blank;
at least two adjacent side panels are joined together by means of a tongue extending from one of these side panels;
this tongue is folded and fixed to the other of these side panels by a weld, such as one produced by hot plate welding or by hot air;
the frame members are joined together by a weld, such as one produced by hot plate welding;
reliefs used for holding the box are provided on frame members;
the blank comprises two outer sheets and an ordered and oriented inner insert arranged between the sheets with which it defines a plurality of cells, and this insert is oriented approximately in the transverse direction of the base of the box;
the thickness of the outer frame is adapted so that it rests on the outer frame of another box when such empty boxes are stacked;
the blank is a cellular polypropylene blank; and
the base has dimensions of approximately 400 mmxc3x97252 mm, the height of the box is approximately 185 mm, the frame has external dimensions of approximately 480xc3x97325 mm, and the frame members have a height of approximately 45 mm and a thickness of approximately 20 mm.
The invention also relates to an assembly comprising a box as defined above and a lid for closing this box, the lid comprising a board and a peripheral rim adapted to surround with slight play the outer reinforcing frame, used for holding the box, when the latter is closed by the lid.
In certain particular embodiments, the assembly may possess one or more of the following features, taken in isolation or in all technically possible combinations:
the board of the lid is provided on its outer face with locating stops designed to surround with slight play the base of another box and thus allow several boxes closed by their lids to be stacked;
the rim of the lid widens out away from the latter and the board of the lid has recesses on its inner face to house locating stops of another lid to enable several lids to be stacked;
the outer face of the board of the lid includes a sunken area with reliefs to limit adhesion to it; and
the lid includes reliefs or depressions to guide the binding straps.